(April 18) -- American Idol isn't just TV's top series. It's a competition-chewing monster. Up 14% in this fifth season, its most-watched yet, Idol is so big — and has such broad appeal — that rival shows are reduced to competing for crumbs.

ABC comedies According to Jim and Hope & Faith have earned their lowest numbers yet opposite Idol's warblers. NBC's Winter Olympics fell far behind, often by a 2-to-1 ratio, while Biggest Loser was, well, a loser and Joey's return lasted all of a week. Even Lost is down about 20% since Idol's results show began airing against it in late February.

Yet as big as it is — and Idol is averaging more than 30 million viewers this season — only one in four potential viewers tune in.

Put another way, "almost three-fourths of viewers watching TV Tuesday at 8 are not watching Idol," says ABC scheduling chief Jeff Bader. "There must be something that can successfully compete against it; it's just that no one has found it yet."

Idol does have its weak spots, relatively speaking: Teenage boys are far less devoted than girls. And the show is least dominant among older adults, which explains why CBS' NCIS and Criminal Minds have fared better against it: Last Tuesday, NCIS claimed 18% of viewers 50 and older, a close second to Idol's 21% share.

"There's a true drama fan that is not going to be enticed by reality shows," says CBS research chief David Poltrack, who chalks up NCIS' military muscle to its older audience profile, which makes it "invulnerable to the impact of Idol," whereas Lost's younger, family audience overlaps with the singing show.

Still, it's mostly a losing battle, says Sam Armando, TV research director at media buyer Starcom, who compares Idol to the unstoppable heyday of NBC's ER in the mid-1990s: "We never saw what the networks considered their best programming against it," he says.

"That's what's been the trend here," as rival networks are "sticking with what they have, knowing it's going to get killed vs. trying something new," Armando says. And moving a hit show against it is simply "too much of a risk" until the Idol train slows, Armando says. "A lot of people thought this would be the year the show would start to decline, but the opposite happened."

That has helped Fox climb to a close second for the season among young adults: As of last week, the network trailed ABC by just 130,000.

And there's more to come: By the time a winner is crowned on May 24, Fox will have aired 45 hours of Idol this season — the most yet — a figure that's up from 381/2 hours last year.